Electrical discharge device



Oct. 22, 1946. E. F. LOWRY ET AL ELECTRICAL DISCHARGE DEVICE Filed July 8, 1943 iNVENTORs. ERWIN E Lowm BY-FIELDING RRosaas M ATTORNEY Patented Oct. 22, 1946 H uNirao STA-res P T orricfa ELECTRICAL DISCHARGE DEVICE Erwin F. Lowry, Swampscott, and Fielding P. Rogers, Danvers, Mass, assignors to Sylvania Electric Products Inc., Salem, Mass; 'a corporation of Massachusetts Application July '8, 1943, Serial No. 493,934

, 1 Claim.- (Cl. 1376122) charge lamp arranged for automatic regulation of the discharge are Further objects, advantages and features will be apparent fromthe following specification taken inconjunction with the accompanying drawing, in which:

Figure 1 is a perspective View of a lamp embodying this invention;

Figure 2 is an enlargement of Figure 1, broken and cut away to show the electrodes and their leads.

Figure 3 is a schematic operating wiring diagram of the structure of Figures 1 and 2;

Figure 4 is a schematic operating wiring diagram of an alternate structure; and

Figure 5 is an illustration of the alternate structure of Figure 4.

While this invention may readily be used in a variety of discharge devices, the illustrative embodiment herein shown and described comprises a small fluorescent bulb in dimension of the order of one inch by two inches and is designed for use on low voltage direct current of the order of -30 volts. This bulb contains argon and mercury; has an anode and a cathode for supporting an electron discharge, and a heater element for heating the cathode to emission. The electron discharge activates a coating of fluorescent material on the bulb, and this coating in turn gives off ultra-violet rays.

A particular use for this lamp is in so-called black light arrangements wherein the visible rays from the lamp are filtered out, usually by means externally of and separate from the lamp, and the ultra-violet rays are used to activate visible ray emanating fluorescent material on an object such as, for example, the dial of an instrument.

Accordingly, the particular lamp in illustration utilizes an argon, mercury and fluorescent mate rial combination designed to produce a maximum of ultra-violet radiation and a minimum of visi- Lamps embodying this invention have the par-'- ticular advantage of a self-starting characteristic. The lamp issimply plugged in on a live line and the cathode is automatically heatedto emission, and the discharge arc is automatically initiated between the cathode and anode, with no external switching being necessary.

Further; this device automatically regulates itself so as to keep the cathode at the right temperature forproper emission. In operation the dischargeareand the cathode heater are arthrough the cathode heater is increased'and the cathode again heated to such emission as will produce the desired discharge arc. Before the arc isstruck the voltagedropacrossthe cathode heater is of the order of 18 volts. When the arc is operating normally the voltage drop across the cathode heater is of the order of 12 volts, and that across the arc is of the order of 12 volts.

This'bulb may be simply and easily mounted in or removed from a socket, just as an incandescent bulb may be handled.

As in Figure 1, the lamp comprises a bulbous glass envelope I, mounted on a brass base sleeve 2 with electrode lead contacts 3 and 4 held in an insulation body 5 which may be glass or other suitable insulation. A third electrode lead contact Gconnects with the base sleeve 2. The sleeve 2 has brass pins 1 extending outward laterally for use in mechanically and electrically mounting the lamps in a socket, as for example in a bayonet type connection.

In Figure 2 the anode lead 8 and the cathode heater leads 9 and Ill are shown sealed in the 'flare sleeve II and extending to their respective contacts 3, 4, and 6. The cathode I2 is mounted on heater lead 9 and the anode I3 is mounted on anode lead 8. Tube I4 is for evacuation of the bulb, and for the introduction of argon and mercury.

During operation of the lamp, leads 8 and ID.

are connected to each other externally of the lamp, see Figure 3.

The cathode I2 is a cylindrical nickel sleeve, open at the bottom, closed at the top, and with its outer central surface coated with bariumstrontium oxides as electron emissive material. The cathode heater I5 is a tungsten coil, located within the cathode sleeve I2 and insulated therefrom through a coating of aluminum oxide on the tungsten coil. circuits between the turns of the coil and between the coil and the cathode sleeve l2. The anode l3 This coating prevents short is molybdenum in the-form of a split ring located below the cathode l2 and lying in a plane substantially perpendicular to the longitudinal axis of the cathode cylinder.

Figure 3 illustrates the operating circuit of the lamp of Figures 1 and 2. The end of the lamp circuit is demonstrated by the contacts 3, 4, and 6, which are the same as those in Figures 1 and 2. The external circuit comprises a battery power supply IS with ballast l1 and-switch l8. The whole circuit is thus shown to have a parallel arrangement with the cathode heater IS on one side and the anode, the cathode, and the discharge path defined thereby, on the other side.

Switch [8 is closed to energize the external circuit, and the lamp contacts 3, 4, and 6, are en gaged with contacts 3a, 4a, and 6a, to energize the lamp. Thereafter, the cathode heater l5 automatically heats the cathode l2 to emission. If the arc fails, wholly or in part, the heating effect of the: heater I5 is automatically varied to again bring the arc to proper discharge.

The alternate structure of Figures 4 and 5 provides a two-contact arrangement whose operationis the same as that of the structure of Figures 1-3.

The anode I9 is positioned above the cathode sleeve 20, the sleeve 20 is supported by lead 2| from above, and the heater element has one end 1'- connected to the inside t'op of the sleeve 20 and the other to anode lead 22. The lamp contacts 23 and 24, Figure 4, are comparable to the contacts 3 and 4 of Figur 1 and the external circuit has a battery 25, ballast 26, and switch 21, and

operates through contacts 23a and 24a. in like manner with respect to the external circuit of Figure 3.

In both structures, the cathode heaters lie substantially completely within their respective cathode sleeves.

The circuit of Figure 4 is arranged in parallel in similarity with that of Figure 3.

We claim:

A low voltage direct current gaseous discharge lamp comprising a bulbous envelope having an 'ionizable atmosphere therein for enclosing its elements, a hollow cylindrical cathode centrally and vertically positioned within said envelope and having its upper end closed, a lead wire extending outside of said envelope and connecting with and supporting said cathode, a heater having its coils within and electrically insulated from said cathode having one of its terminals connected to the cathode, an anode comprising an elongated loop of wire, substantially circular in form, disposed concentric with said cathode, in

'a plane perpendicular thereto but substantially therebelow, the diameter of said anode being considerably smaller than the greatest diameter of the bulbous envelope and smaller than the diameter of the neck of the bulbous envelope, a second lead wire extending to the outside of said envelope connected with and acting to support said anode and a third lead wire connected to the other terminal of said heater and extending outside of said envelope whereby said heater coil and the are between the anode and cathode may be supplied by the same or by separate sources of energy.

ERWIN F. LOWRY.

FIELDING P. ROGERS. 

